Posts Tagged ‘mutation’
“The past lives within the present, and our ancestors breathe through our children”*…
Indeed, that’s true all the way back. And as Jonathan Lambert explains, we now have more visibility on that distant past. The emerging understanding of our “last universal common ancestor” suggests it was a relatively complex organism living 4.2 billion years ago, a time long considered too harsh for life to flourish…
If you follow any path of ancestry back far enough, you’ll reach the same single point. Whether you begin with gorillas or ginkgo trees or bacteria that live deep in the bowels of the Earth — or yourself, for that matter — all roads lead to LUCA, the “last universal common ancestor.” This ancient, single-celled organism (or, possibly, population of single-celled organisms) was the progenitor of every varied form that makes a life for itself on our planet today.
LUCA does not represent the origin of life, the instance whereby some chemical alchemy snapped molecules into a form that allowed self-replication and all the mechanisms of evolution. Rather, it’s the moment when life as we know it took off. LUCA is the furthest point in evolutionary history that we can glimpse by working backward from what’s alive today. It’s the most recent ancestor shared by all modern life‚ our collective lineage traced back to a single ancient cellular population or organism.
“It’s not the first cell, it’s not the first microbe, it’s not the first anything, really,” said Greg Fournier, an evolutionary biologist at the Massachusetts Institute of Technology. “In a way, it is the end of the story of the origin of life.”
Still, understanding LUCA — whether it was simple or complex, and how quickly it emerged after life’s origin — could help answer some of our deepest questions about where we come from and whether we’re alone in the universe.
“[LUCA] tells our own story,” said Edmund Moody (opens a new tab), an evolutionary biologist at the University of Bristol. “It gives us a point from which we can look even further back.”
For half a century, biologists have focused on different kinds of physiological, genomic and fossil evidence to paint portraits of LUCA that sometimes clash dramatically. In 2024, Moody and a team of interdisciplinary researchers, including geologists, paleontologists, system modelers and phylogeneticists, combined their knowledge to build a probabilistic model that reconstructs modern life’s shared ancestor and estimates when it lived.
The analysis, published in Nature Ecology and Evolution in July, sketched a surprisingly complex picture of the cell. LUCA lived off hydrogen gas and carbon dioxide, boasted a genome as large as that of some modern bacteria, and already had a rudimentary immune system, according to the study. Its genomic complexity, the authors argue, suggests that LUCA was one of many lineages — the rest now extinct — living about 4.2 billion years ago, a turbulent time relatively early in Earth’s history and long thought too harsh for life to flourish.
The analysis reaches two conclusions that seem in conflict with each other, according to Aaron Goldman, who studies the molecular evolution of early life at Oberlin College and wasn’t involved in the new research. “The first is that LUCA was a complex cellular organism that likely lived in a complex ecological setting,” he said. “The second is that LUCA dates to a time that is pretty early in the history of Earth.” The results could mean that life evolved from a simple replicator into something resembling modern microbes remarkably quickly, he said. “That’s really exciting.”
“Our work suggests that those early steps of evolution weren’t hard; they’re pretty easy,” said co-author Phil Donoghue, an evolutionary biologist at the University of Bristol. “If you’re concerned with the origin of microbial-grade life, then that’s apparently very easy, and it should be quite common in the universe.”
Not all experts in the field agree, however. Some argue that a few hundred million years is not enough time for complex life to have evolved. The authors stress that their analysis is a first attempt to paint a fuller, admittedly fuzzy, picture of LUCA. “I fully expect and hope people prove us wrong in certain aspects,” said Moody, the paper’s lead author, especially if those new results offer a clearer view of the ancient ancestor of all life we know…
Eminently worth reading in full: “All Life on Earth Today Descended From a Single Cell. Meet LUCA,” from @evolambert in @QuantaMagazine.
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As we look back, we might send microscopic birthday greetings to Lewis Thomas; he was born on this date in 1913. A physician, poet, etymologist, essayist, administrator, educator, policy advisor, and researcher, he distinguished himself in medicine and microbiology both for his suggestion that an immunosurveillance mechanism protects us from the possible ravages of mutant cells (an idea later championed by Macfarlane Burnett) and for his proposal that viruses have played a major role in the evolution of species by their ability to move pieces of DNA from one individual or species to another.
But Lewis is more widely known for his writing, perhaps most especially for his first two books– The Lives of a Cell: Notes of a Biology Watcher (which won National Book Awards in two categories) and The Medusa and the Snail: More Notes of a Biology Watcher (which won another National Book Award)– which underscored the interconnectedness of life by sketching the ways that what is seen under the microscope is similar to the way human beings live.
“It is sad to go to pieces like this but we all have to do it”*…
Still, some species “do it” differently than others…
It is well known that somatic mutations — mutations in our body’s genetic code that accumulate over time — can cause cancer, but their broader role in ageing is less clear.
Now a team of researchers have measured the somatic mutation rates of a range of mammals and discovered a striking correlation between mutation rate and lifespan. Lending evidence to the theory that somatic mutations are a cause of ageing rather than a result of it…
Ageing is linked to accumulated mutations: “The lifespan secret: why giraffes live longer than ferrets,” from @Nature.
* Mark Twain, on aging
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As we grow old gracefully, we might send carefully-deduced birthday greetings to William Ian Beardmore (WIB) Beveridge; he was born on this date in 1908. A veterinarian who served as director of the Institute of Animal Pathology at Cambridge, he identified the origin of the Great Influenza (the Spanish Flu pandemic, 1918-19)– a strain of swine flu.
“How is it that you keep mutating and can still be the same virus?”*…
A common plant has yielded insights that question a fundamental assumption in biology– more specifically, an assumption about the mechanism of natural selection…
A simple roadside weed may hold the key to understanding and predicting DNA mutation, according to new research from University of California, Davis, and the Max Planck Institute for Developmental Biology in Germany.
The findings, published today in the journal Nature, radically change our understanding of evolution and could one day help researchers breed better crops or even help humans fight cancer.
Mutations occur when DNA is damaged and left unrepaired, creating a new variation. The scientists wanted to know if mutation was purely random or something deeper. What they found was unexpected.
“We always thought of mutation as basically random across the genome,” said Grey Monroe, an assistant professor in the UC Davis Department of Plant Sciences who is lead author on the paper. “It turns out that mutation is very non-random and it’s non-random in a way that benefits the plant. It’s a totally new way of thinking about mutation.”
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Knowing why some regions of the genome mutate more than others could help breeders who rely on genetic variation to develop better crops. Scientists could also use the information to better predict or develop new treatments for diseases like cancer that are caused by mutation.
“Our discoveries yield a more complete account of the forces driving patterns of natural variation; they should inspire new avenues of theoretical and practical research on the role of mutation in evolution,” the paper concludes.
Evolutionary theory revised? A new study challenges the received wisdom that that DNA mutations are random. Read the underlying paper here.
* Chuck Palahniuk, Invisible Monsters
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As we contemplate change, we might send micro-biological birthday greetings to Ruth Sager; she was born on this date in 1918. A geneticist, she had two careers in science.
In the 1950s and 1960s, she pioneered the field of cytoplasmic genetics by discovering transmission of genetic traits through chloroplast DNA, the first known example of genetics not involving the cell nucleus. The academic community did not acknowledge the significance of her contribution until after the second wave of feminism in the 1970s.
Then, in the early 1970s, she moved into cancer genetics (with a specific focus on breast cancer); she proposed and investigated the roles of tumor suppressor genes.
“I like it when a flower or a little tuft of grass grows through a crack in the concrete. It’s so f#@kin’ heroic.”*…
From dilapidated power plants, abandoned medical facilities, and amusement parks left in rusted ruin, the compelling scenes that French photographer Jonathan Jimenez, aka Jonk (previously), captures are evidence of nature’s endurance and power to reclaim spaces transformed by people. Now compiled in a new book titled Naturalia II, 221 images shot across 17 countries frame the thriving vegetation that crawls across chipped concrete and architecture in unruly masses.
This succeeding volume is a follow-up to Jonk’s first book by the same name and focuses on the ways the ecological crisis has evolved during the last three years. He explains the impetus for the book in a statement:
On the one hand, the situation has deteriorated even further with yet another species becoming extinct every single day. Global warming continues and has caused repeated natural catastrophes: floods, fires, droughts, etc. On the other hand, our collective awareness has widely increased. We are still a long way from the commitment needed to really change things, but we are heading in the right direction. Millions of initiatives have already emerged, and I hope that my photos and the message contained within them can play a small part in the collective challenge facing us all…
More at “Nature Resurges to Overtake Abandoned Architecture in a New Book of Photos by Jonk” and at his site.
On an apposite note: “Forest the size of France regrown worldwide over 20 years, study finds.”
* George Carlin
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As we inspect the inexorable, we might spare a thought for Hugo Marie de Vries; he died on this date in 1935. A botanist, he introduced the experimental study of organic evolution– and was, thus, was one of the first geneticists. His rediscovery in 1900 (simultaneously with the botanists Carl Correns and Erich Tschermak von Seysenegg) of Gregor Mendel’s principles of heredity and his theory of biological mutation, though considerably different from a modern understanding of the phenomenon, resolved ambiguous concepts concerning the nature of variation of species that, until then, had precluded the universal acceptance and active investigation of Charles Darwin’s system of organic evolution.
He suggested the concept of genes and introduced the term “mutation”, and developed a mutation theory of evolution.
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